Ecological contrasts across an Antarctic land–sea interface

Abstract We report the composition of terrestrial, intertidal and shallow sublittoral faunal communities at sites around Rothera Research Station, Adelaide Island, Antarctic Peninsula. We examined primary hypotheses that the marine environment will have considerably higher species richness, biomass and abundance than the terrestrial, and that both will be greater than that found in the intertidal. We also compared ages and sizes of individuals of selected marine taxa between intertidal and subtidal zones to test the hypothesis that animals in a more stressed environment (intertidal) would be smaller and shorter lived. Species richness of intertidal and subtidal communities was found to be similar, with considerable overlap in composition. However, terrestrial communities showed no overlap with the intertidal, differing from previous reports, particularly from further north on the Antarctic Peninsula and Scotia Arc. Faunal biomass was variable but highest in the sublittoral. While terrestrial communities were depauperate with low biomass they displayed the highest overall abundance, with a mean of over 3 × 10⁵ individuals per square metre. No significant differences in ages of intertidal and subtidal individuals of the same species were found, with bryozoan colonies of up to 4 years of age being present in the intertidal. In contrast with expectation and the limited existing literature we conclude that, while the Antarctic intertidal zone is clearly a suboptimal and highly stressful habitat, its faunal community can be well established and relatively diverse, and is not limited to short‐term opportunists or waifs and strays.     

Black Point is associated with reduced levels of stress, disease- and defence-related proteins in wheat grain

Black Point in wheat is a dark discoloration at the embryo end of the grain, which causes substantial financial losses to wheat growers due to down-grading of otherwise high-grade wheat. There does not appear to be a single cause for Black Point, although evidence suggests that fungal infection is the main link to Black Point symptoms. We sought to identify grain proteins from Black Point-affected and Black Point-free wheat cultivar SUN239V, which is known to be very susceptible to Black Point. The proteomes of both the germ and endosperm-bran components of Black Point-affected and Black Point-free grain were compared using two-dimensional gel electrophoresis (2-DE) with six replicate gels run for each protein sample. Approximately 1478 discrete protein spots were found in 2-DE gels from the germ fraction of the grain, of which 354 were identified by mass spectrometry (MS). Similarly, 1360 discrete protein spots were found from the endosperm-bran fraction, of which 303 were identified by MS. No proteins of fungal or bacterial origin were positively identified, suggesting that, at least in some cases, Black Point is not associated with microbial activity. Of the germ proteins, 252 were differentially expressed in Black Point-affected tissue, with 67 of these proteins identified by MS. Of the endosperm-bran proteins, 317 were differentially expressed in Black Point-affected tissue, with 86 identified. The largest of 12 functional classes to which the differentially abundant proteins were assigned was the 'stress' class, i.e. products of genes associated with stress, disease and defence. Higher levels of these proteins were found in Black Point-free grain, suggesting that protection from the disease might be afforded by increased levels of the 'stress' proteins.     

Development and reproduction of Bemisia tabaci （Homoptera： Aleyrodidae） on three bean species

Abstract The development, survivorship and reproduction of Bemisia tabaci B-biotype on three bean species were studied at 26±1°C in the laboratory. The developmental periods from egg to adult varied from 27.80 days on garden beans to 18.20 days on soybeans. The survivorship from egg to adult on soybeans, cowpeas and garden beans was 77.14, 70.14 and 64.28%, respectively. The average longevity of female adults ranged from 12.30 days on soybeans to 9.80 days on garden beans, and the oviposition of B. tabaci varied from 160.85 eggs on soybeans to 98.00 eggs on garden beans. Life table parameters were calculated as biological attributes for Bemisia tabaci populations fed on three bean species. The results indicated that the intrinsic rate of increase (r_m), the finite rate of increase (λ) and net reproductive rate (R₀) were high for populations fed on soybeans, with values of 0.1857, 1.2041 and 82.1576, respectively. The corresponding values were less for populations fed on garden beans, with values of 0.1097, 1.1159 and 31.2661, respectively. The parametric values for cowpeas were intermediate between soybeans and garden beans but no significant difference were observed for the r_m values for soybeans and cowpeas. Experimental evidence in our investigation indicated that Bemisia tabaci is best adapted and shows the greatest preference for soybean of the three bean species tested in this study.     

Phylogenetic relationships of the north-eastern Atlantic and Mediterranean blenniids

The phylogenetic relationships of 27 north-eastern Atlantic and Mediterranean blennioids are analysed based on a total of 1001 bp from a combined fragment of the 12S and 16S mitochondrial rDNA. The most relevant results with implications in current blenniid taxonomy are: (1) Lipophrys pholis and Lipophrys (=  Paralipophrys ) trigloides are included in a well-supported clade that by the rule of precedence must be named Lipophrys ; (2) the sister species of this clade are not the remaining species of the genus Lipophrys but instead a monotypic genus comprising Coryphoblennius galerita ; (3) the smaller species of Lipophrys were recovered in another well-supported and independent clade, which we propose to be recognized as Microlipophrys ; (4) although some authors included the genera Salaria and Lipophrys in a single group we have never recovered such a relationship. Instead, Salaria is more closely related to the genera Scartella and Parablennius ; (5) the genus Parablennius , which was never recovered as a monophyletic clade, is very diverse and may include several distinct lineages; (6) the relative position of Aidablennius sphynx casts some doubts on the currently recognized relationships between the different blenniid tribes. Meristic, morphological, behavioural and ecological characters support our results and are also discussed. The possible roles of the tropical West African coast and the Mediterranean in the diversification of blenniids are discussed.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 86 , 283–295.     

Effect of season of burning and removal of herbaceous cover on seedling emergence in a eucalypt savanna of north‐eastern Australia

Abstract Seedling emergence in a eucalypt savanna of north‐eastern Australia was documented over a 12‐month period, between May 1999 and May 2000. Seedling emergence for grasses, forbs and subshrubs was found to mainly occur in a brief pulse at the start of the wet season following fire or the removal of grass biomass. Only a minor number of tree and shrub seedlings were detected overall. Burning, or cutting away the grass layer in unburnt savanna, in both the early (i.e. May) and the late (i.e. October) dry seasons significantly increased seedling emergence over undisturbed savanna that had been unburnt for 3 years. Removing the grass layer in unburnt savanna, during either the early or the late dry season, triggered similar seedling densities to savanna burnt in the early dry season. Late dry season fires promoted the greatest seedling density. We attribute this to the higher intensity, late dry season fires releasing a greater proportion of seed from dormancy, coupled with the higher density of soil seed reserves present in the late dry season.     

Ten microsatellite loci for evolutionary research on Nesospiza buntings

We tested 19 loci originally developed for Vidua and Geospiza, of which six Vidua loci were polymorphic and furthermore, developed four microsatellite loci for Nesospiza buntings. Allelic variation ranged from two to 13 alleles, with heterozygosity from 0 to 0.82. Ascertainment bias was evident as increased allelic diversity of loci developed for Nesospiza, versus those developed for Vidua. Two loci showed linkage, and several, deviation from Hardy–Weinberg equilibrium. We suggest such deviations are through introduction of new alleles by introgression, or of the Wahlund effect. These loci will contribute to the understanding of speciation in Nesospiza buntings of the Tristan da Cunha islands.     

Effect of temperature and high pressure on the activity and mode of action of fungal pectin methyl esterase

Pectin was de-esterified with purified recombinant Aspergillus aculeatus pectin methyl esterase (PME) during isothermal-isobaric treatments. By measuring the release of methanol as a function of treatment time, the rate of enzymatic pectin conversion was determined. Elevated temperature and pressure were found to stimulate PME activity. The highest rate of PME-catalyzed pectin de-esterification was obtained when combining pressures in the range 200-300 MPa with temperatures in the range 50-55 degrees C. The mode of pectin de-esterification was investigated by characterizing the pectin reaction products by enzymatic fingerprinting. No significant effect of increasing pressure (300 MPa) and/or temperature (50 degrees C) on the mode of pectin conversion was detected.     

Structural characterization of tissue-specific galactan from flax fibers by 1H NMR and MALDI TOF mass spectrometry

A high-molecular-mass polysaccharide galactan (M 2000 kDa) was isolated from flax at the stage of cell wall thickening of the bast fiber development. The polymer structure was studied by ¹H NMR spectroscopy and MALDI TOF mass spectrometry. It is built up of Gal (59%), Rha (15%), GalA (23%), and Ara (3%) residues. The galactan backbone consists of successively alternating monomer disaccharide units (→ 4GalA1 → 2Rha1 →)_n and is similar in its structure to the backbone of rhamnogalacturonan-1 (RG-I). Rhamnose residues bear in position 4 β-(1 → 4)-galactose side chains of various lengths with a polymerization degree of up to 28 or higher. A part of the side chains have branchings.